Heretofore, continuously stirred tank reactors (CSTRs) and especially catalytic recycle reactors (RRs), have all had a rotating shaft, most of it extending through the reactor body. The outside end was usually attached to a drive motor while the inside end supported the rotor of the blower. For example, U.S. Pat. No. 2,689,267 to Rollman relates to a reaction vessel to manufacture polymerized olefins employing granular catalyst in a basket and having an impeller therein. The impeller circulates the reacting materials and is connected to an external power source via a shaft which extends through the bottom of the reaction vessel. Such shaft must be sealed and hence the vessel is subjected to leaks, loss of pressure, and the like.
U.S. Pat. No. 2,301,044 to Heard relates to a catalyzed hydrocarbon reaction wherein no mechanical device for mixing or circulating is utilized. Rather, the feed stream, brought to an increased pressure by a pump, is discharged through a nozzle into a jet pump of the Venturi type and the resulting jet-pumping action creates the recirculation and mixing.
In a jet-pump type reactor, the recirculating flow rate is proportional to the feed flow discharged through the nozzle. Therefore, when the feed flow increases, both space velocity (in standard cubic feet per hour of total circulating gas per cubic feet of catalyst per hour =SCFH/cu.ft./hr.), and the mass velocity (expressed in lbs./sq.ft./hr.) are changing in the same ratio. Whereas, in internal recirculation reactors using a rotating blower, space velocity can be changed by changing the feed, while mass velocity remains unchanged since it depends on the blower rotor speed only. Changing blower rotor speed, at constant feed rate, changes the mass velocity only but does not effect the space velocity. This independence of the two kind of velocities is one of the major advantages of recycle reactors and this is lost in jetpump type recycle reactors.
In an article on "Reactor for Vapor-Phase Catalytic Studies," Chemical Engineering Progress, Volume 70, No. 5, May 1974, Berty, the present inventor herein, discusses an autoclave type reactor with regard to permitting catalyst testing and reaction kinetic studies. To overcome leaking and contamination problems, he utilizes a commercially available "Magnedrive" type shaft (Magnedrive is a registered trade name of Autoclave Engineers, Inc.). Using this shaft eliminates leaking and most contamination problems, but adds a long, heavy shaft that extends from the body and has some added dead volume around it. The long heavy shaft increases cost, size, and it requires graphite or RULON bearings. These bearings are used without lubrication and their wear products can cause some contamination even if the rotational speed is limited to a few thousand RPM. At higher RPMs, they wear out rapidly and increasingly contaminate the reactor by their wear products (RULON is a trademark of DuPont Co., and it is an iron oxide filled Teflon material).
In an article presented at the Spring National Meeting of the American Institute of Chemical Engineers in Houston, Texas on March 27-31, 1983, Berty describes a new generation of internal recycle reactors. These smaller and lighter reactors are easier to operate, but they still require a shaft to drive and to support the blower rotor. Page 5 of the article discusses future possibilities such as a shaftless model, where the blower rotor is suspended and supported by the feed fluid, much like a rotameter float is suspended by the flowing fluid in a conical tube. Rotating force is transmitted either by magnetic coupling or by the energy of an excess, higher pressure feed to the rotor.
In a similar paper presented at the November 1983 Diamond Jubilee Meeting of the American Institute of Chemical Engineers in Washington, D.C., Berty discusses the general history of various types of laboratory recycle reactors and continuously stirred reactors in general and also notes the conceptual design of the instrument set forth immediately above.
Except for the two recent Berty articles, the other publications and patents do not suggest any instruments, based on the recirculation reactor principle where the blower rotor is suspended by the feed fluid and is used to measure reaction rates.